Electric controlling apparatus



March 4, 1941- R. A. ANDREWS 3 ELECTRIC CONTROLLING APPARATUS Filed April 16,1940 2 Sheets-Sheet 1'.

INVENTOR flaws A. r9A/0/P5Ws March 4; 1941. ANDREWS 2,234,104

ELECTRIC CONTROLLING APPARATUS Filed ApriLl-G, 1940 2 Sheets-Shet '2 J;l C..

6 1% led-C INVENTOR flax-0.579. fl/Vfl/FEWS 162% WHO R N EY Patented Mar. 4, 1941 UNITED STATES 2,234,164 ELECTRIC CONTROLLING APPARATUS Rufus A. Andrews, Mamaroneck, N. Y., assignor to Ward Leonard Electric Company, a corporation of New York Application April 16, 1940, Serial No. 329,847

14 Claims. (Cl. 171-119) This invention relates to the control of voltage regulating apparatus for dynamo-electric machines having a field winding and particularly relates to switching means by which the con- 5 trol is changed from manual control to automatic regulation and from automatic regulation to .manual control. Such control is convenient at times for replacement of parts or repair of the automatic regulating means and also may be used when placing machines in parallel and under various other conditions.

The particular form of the regulating apparatus forms no part of the present invention, although it is well adapted to particular types,

15 such as those using electronic tubes and to various other forms. The change from automatic regulation to manual, or the reverse, should be accomplished by automatic switching devices so as to insurethe making and breaking of the proper connections and the proper sequence of steps and of their timing in the change. It is also important in passing from one condition to the other that the voltage of the dynamo controlled should not be subjected to an objectional change. 1

In the pending application of Frank G. Logan, Serial No. 77,931, filed May 5, 1936, a form of automatic switch control is disclosed which secures proper action in passing from manual to automatic regulation but in changing irom automatic control to manual control there is a momentary interval between the removal of the automatic control and the assumption of the manual control which results in a dip in voltage of the regulated machine; also in changing back to automatic control, the electronic tubes require reheating and the. time thus occupied is sometimes inconvenient.

The main object of the present invention is to provide automatid switching means which will insure the proper sequence of steps and of their timing in-passing from manual to automatic regulation and also in passing. from automatic regulation to manual. Another object is to avoid the necessity of preheating the electronic'tubes or conditioning of other parts in order .to pass from manual to automatic regulation each time spch change is made. Another object is to provide a simple and dependable form of switch controlling apparatus for accomplishing the desired results. Other objects and advantages will be understood from the following description. and accompanying drawings which illustrate preferred embodiments of the invention.

Fig. 1 is a diagram showing one embodiment of the invention; and Fig. 2 is a diagram showing another embodiment thereof.

Although this invention is applicable to various forms and types of automatic regulators 5 it is well adapted for use in connection with the form of regulator disclosed in said pending application; and a description thereof is included herein in order to show one embodiment of this invention as applied thereto. The regulator 1 described is for maintaining substantially constant the output voltage of an alternating current generator, regardless of change of load or other conditions which would afie'ct the voltage. Referring to Fig. l, a three-phase alternating 15 current generator I is indicated delivering cur-- rent to the supply mains 2. The field winding 3 of the generator is supplied with current from the armature 4 of an exciter having a field winding 5. 20

When the automatic regulation is not being used, a relay magnet coil C having two movable contacts to and 6b is deenerglzed and its movable contacts are in their-lower position as shown engaging fixed contacts. The movable contact 25 6b is connected to one terminal of the exclter field winding 5 and its fixed contact is connected througha manually adjustable resistance to a terminal of the exciter armature 4, the other terminal of which is connectedto a-terminal of 30 its field winding 5. Thus when the automatic regulation is not in use, the field winding of the exciter is connected through the resistance I in shunt to the armature l, iormi'ng an auxiliary circuit for the field winding. Manual 'adjust- 35 ment of-the resistance 1 may be made to cause the exciter to deliver current to the field windmg} of the generator of such value as will cause the alternator to generate a voltage of about the desiredvalue. A manually adjustable re- 40 sistance l is in series with the field winding 3 of the alternator for obtaining further desired adjustment of the generator voltage. Another magnetic relay for automatic control of the switching means is provided having a winding 45 9 and a plurality of movable contacts la, Oh and 9c. The movable contacts are adapted to engage fixed contacts as shown when the relay 9 is energized or deenerglzed, the position or the contacts beingshown when the coil 9 is de--- 50 energized.

Across a pair of conductors of the three-phase generator is connected a transformer Illa, the secondary of which supplies current to a pair of leads I l and I: throu h a switch II. when this. 4

' spcndingly changing switch is closed, a voltage is imposed upon the conductors II and I2 derived from and corresponding with the voltage, or change oi voltage, of one phase of the alternator. The lead I2 is connected to one terminal 01' the winding 8 through a normally open pushbutton switch I3. This terminal of the winding 9 is also connected to the movable contact 6a of the magnet l and when the latter is energized, the contact la engages a fixed contact lc which is connected to the line I2. One terminal of the winding 6 is connected to the line II and its other terminal connected .to the movable contact la 01 the magnet 9. When the latter is energized, the contact la engages a fixed contact ld which is connected through a normally closed pushbutton switch II to the upper terminal the winding l. The lower terminal of the winding 9 is connected to the lead II while its upper terminal, as already stated, is connected to a terminal 0! the normally open pushbutton switch ll, the other terminal of which is connected to lead I2.

At the right of the drawings is indicateda transformer having a primary winding I and several secondary windings Ila, Ilb, Ilc, lid and lie. The primary is connected across the leads II and I2 and when the switch III is closed, is subjected to the voltage derived from one phase of the generator. The secondary winding Ila is connected to opposite terminals, through an adjustable resistance ll, of a bridge-connected rectii'ler unit I1 indicated as having individual sections of the copper oxide type connected in the four branches of the bridge so as to give a positive and negative voltage across the other two terminals of the bridge. The resistance I6 is manually adjustable for the purpose of adjusting the output voltage or the generator I to give any desired constant voltage. From the upper negative terminal of the bridge ll, connection is made to the cathode Ila of a space discharge tube ll having an anode Ilb. From the cathode, or filament Ila, a return connection is made to the positive terminal of the bridge I! through a resistance ll.

The secondary winding Ilb or the transformer has one terminal connected to the filament Ila and the other terminal connected through a high resistance 20 to the plate Ilb of the tube ll. It will thus be seen that any change in voltage of the generator I will be reflected in a corresponding change oi! voltage at the terminals of the bridge-connected rectifier I! and in the value of the direct current delivered through the filament Ila and resistance II. This change 01' current through the filament results in correits temperature. The change in temperature causes the resistance of the tube ll to greatly change giving a greatly amplified variation in the resistance of the plate circuit of the tube upon slight change in voltage of the generator I. The plate circuit is from one terminal of the secondary Ilb through the high resistance 20 to the plate llb, then to the filament Ila and back to the other terminal of the secondary llb. The change in current through the high resistance 20 causes a corresponding change in the voltage'drop in this resistance, resulting in the potential of the plate Ilb being greatly changed in response to a slight departure from normal of the voltage or generator I.

A three-element space discharge tube 2| is indicated having a cathode or filament 2Ia, a plate lib and a grid 2 lo. The grid is electrically connected to a point between the plate Ilb and a terminal of the resistance III. Thus the grid He is subjected to the change of potential imposed upon this point in the manner just described. The secondary winding I5c has its terminals connected to a resistance 22 engaged by an adjustable contact 22a. This contact is connected to a point between one terminal of the secondary l5!) and a terminal of the resistance 20. A terminal of the secondary lie is connected to the mid-point oi the secondary winding Ild, the terminals of which supply heating current to the filament 2Ia. Thus the grid circuit of tube 2| passes from the right-hand terminal of the secondary winding I5c to the mid-point of the secondary I5d and then from its outer terminals to the filament 2Ia, thence to the grid He and thence through resistance 20 to the contact 22a and then through the resistance 22 to the winding I50. The connections are in such relation that the electromotive force imposed upon this grid circuit by the secondary winding I50 is in opposition as applied to the resistance 20, to the electromotive force across the resistance 20 due to the current in the plate circuit of the tube ll. The purpose of this opposing voltage applied to the resistance 20 is to bias the potential of the grid 2Ic so as to permit the filament Ila to work in a temperature range which gives the greatest response to change of current in this filament. Adjustment of the contact 22a may be made for imposing the proper bias potential on the grid He.

The secondary winding l5e has one terminal connected to the plate H17 0! tube 2| while the other terminal is connected through a condenser 23 to one terminal of a primary winding 24 of an insulating transformer. The other terminal 0! this primary is connected to a mid-point of the secondary winding I56; and the mid-point of seco dary winding I5d is connected to a point 25 in the connection from the condenser 23 to the primary winding 24 of the transformer. It will thus be seen that the circuit from one lead of the secondary lie passes through a condenser 23 of fixed capacity to the point 2! whereas the circuit from the other lead of the secondary Ile passes to the plate of the tube 2| and through the filament 2Ia to the secondary lid and from its mid-point to the point 25. Theresistance of this'plate circuit varies greatly in response to change of potential of the grid 2Ic as controlled by the previously described apparatus; and this change of resistance in the plate circuit causes the phase of the potential between point 25 and the mid-tap of the winding Ile to greatlychange with reference to the anode potential of a tube 28 in response to a small departure from normal of the voltage of the generator I. This of course changes the phase oi the electromotive force impressed upon the primary 24 of the insulating transformer and correspondingly changes the phase of the electromotive force oi the secondary 2la.

Another transformer is shown in the lower portion of the drawing having a primary winding 28 and secondary windings 28a, 28b and 280. The primary winding is connected across the leads I I and I2. The secondary 26b has its terminals connected to the cathode 21a of a haltwave rectifier 21; and the secondary 28c has its terminals connected to the cathode 28a oi the half-wave rectifier N.

The mid-point of the secondaries 25b and 0 are connected together and also to a terminal of the exciter field winding 5. The right-hand terminal of the secondary winding 26a is shown connected to the movable contact 911 of the relay controlled by the relay coil 9. When this coil is energized,- the movable contact 9b is caused to engage the contact29 which is connected to the anode 21b of the rectifier 21. The lefthand terminal of the secondary 26a is shown connected to the movable contact of the relay and when the coil 9 is energized, the contact 90 engages the contact 30 which is connected to the anode 28b of the rectifier 28. The mid-point of the secondary 26a is connected to the exciter field winding 5 at the terminal where it is connected to a terminal of the exciter armature I. The lead from the mid-point of the secondary 26a is electrically connected to a terminal of the resistance l9 so as to have a common potential therewith for the purpose hereinafter explained.

It is evident that the transformer in the lower portion of the drawings will supplythe exciting current through the rectifiers to the field winding 5 of the exciter when the switch I0 is closed and the'relay coils 6 and 9 are energized. Thus one supply circuit of the exciter winding 5 may be traced from the right-hand terminal of the secondary 26a to the movable contact 9b, contact 29 to anode 21b and then to the cathode 21a to the secondary 26b and thence from its midpoint to one terminal of the field winding 5 and thence back to the mid-point of the secondary 26a.

The circuit from the left-hand terminal of the secondary 28a may be traced to contact 9c, contact 30 and thence to anode 28b, thence to the cathode 28a and through.the secondary 260 to a terminal of the field winding 5 and thence from its opposite terminal back to the mid-point of the secondary 26a. Thus the half-wave rectifiers 21 1 and 28 cooperate to alternately supply current to the exciter field winding 5. The rectifier 28 is provided with a grid 280 which is connected through a resistance 3| to one terminal of the secondary 24a of the insulating transformer, the

other terminal of this secondary being connected to the mid-taps of the secondaries 26b and 260. Thus there is imposed upon the rectifier 28 a grid circuit from the lower terminal of secondary 24a through resistance 3| to the grid 28c and thence to the cathode 28a and through the secondary 26c back to the other terminal of the secondary 24a. As already explained, the phase of the electromotive force of the secondary 24a is shifted widely with reference to the anode voltage of tube 28 in response to a slight change in voltage of the generator I. This change in phase is imposed upon the grid circuit of tube 28 resulting'ln a change in output of the tube.

Shifting the phase of the potential of grid 280 with reference to that of the anode 28b in such direction that the effective controlling potential of the grid is quite negative with respect to the anode 28b results in a minimum amount of current flowing in the anode circuit of tube 28 and results in this tube supplying a small amount of current to the exciter field winding 5 during its half-wave period. This small current results in also causing the tube 21 to deliver a small current to the exciter field winding 5 during its halfwave operation. When the phase of the grid 280 is automatically shifted to cause its eflective controlling potential to be less negative with respect to the anode 28b potential, the current supplied by the tube 28 to the exciter field winding is correspondingly increased during'its active period and likewise causes an increase of current to be delivered to the exciter field winding by rectifier 21 during its half-wa ve operation. Thus there is not only a change in voltage and current supplied to the field winding of the exciter by the rectifier 28 caused by the shifting of the phase of the grid 28c circuit but there is also a change of voltage and current supplied to the field winding of the exciter by the rectifier 21 in response to the action of the rectifier 28. It is evident from the operation of the apparatus disclosed that a slight change in voltage of the generator results in very greatly amplified change in the voltage and current applied to the field winding of the exciter, giving a very pronounced counteracting eflect upon the exciter field winding in response to any tendency of departure from normal voltage of the generator I. Moreover by reason of the character of the apparatus utilized, the corrective eflect applied to the field winding of the exciter is almost instantaneous in itsaction upon the occurrence of any slight departure from normal of the generator voltage, and the rate of change of the armature exciter voltage is determined by the adjustment of the hereinafter explained anti-hunting circuit which is dependent upon the electrical constants of the controlled machine. In this way correction of the controlled alternating current voltage is accomplished while maintaining the electrical stability of the system.

This corrective effect is so. great that it would tend to over-correct the departure from normal voltage which in turn would result in a pronounced counteracting eifect and cause hunting. There is therefore included the provision of an anti-hunting control. For this purpose a condenser 32 is connected between one terminal of the exciter armature 4 and the contact 33 which adjustably engages the resistance l9. This applies an electromotive force to a portion of the resistance l9 which is responsive to change of voltage of the exciter armature 4, by a circuit which passes from the lower positive terminal of the armature I through the condenser 32 to the contact 33 and through the left-hand portion of the resistance 19 back to the negative terminal of the armature 34. This momentary condenser discharge voltage impressed on the resistance I! will act to oppose the voltage applied to resistance 19 by the bridge rectifier unit I! when the voltage of the exciter armature 4 is rapidly decreasing. It will thus oppose and tend to choke the effect of the action of the control apparatus the exciter armature is decreasing, is in opposi-.

tion to the rectifier circuit voltage owing to the direction of discharge of the condenser 32. When however the control apparatus is acting to increase the voltage of the generator I bygreatiy raising the voltage applied to the exciter jfleld -winding, the resultant rapid increasing voltage of the exciter armature causes a voltage to be impressed by the condenser circuit on a portion oi the resistance l9 in the opposite direction from that previously considered because the condenser is then being charged. In that event the condenser circuit voltage acts in a direction to aid the voltage of the circuit of the rectifier i1 and thus tends to counteract the action the control apparatus in raising the voltage of the exciter armature. This counteracting efi'ect of the antihunting means results from the rapid change of current in the field winding or the exciter as aiiected by the control apparatus with the result that any change imposed in each direction is dampened and hunting is avoided. It will be appreciated that the opposing or aiding voltage resulting from the action of the condenser on the resistance I9, correspondingly afi'ects the heating of the filament Ila and in that way dampens the change of current in the circuit of the rectifier I! through the resistance 20. It will also be understood that by providing a direct current for this control circuit containing the resistance 20, it permits the action of the condenser circuit to act with or in opposition to the voltage of the direct current control circuit and thus serves to accomplish the damping of the attempted change in both directions, that is, when the voltage oi the generator is to be raised as well as when it is to be lowered. Adjustment of contact 33 permits the anti-hunting effect to be made the proper amount for obtaining the best results.

Under prolonged manual control, the switch II is opened, and the relay coils 6 and 8 are deenergized. The contact to is then in its lower position as shown and the field winding 5 of the exciter is in shunt to the armature I through the field rheostat I. The main field rheostat I of the main generator is manually adjusted to its proper amount and the field rheostat 1 oi! the exciter is likewise adjusted to its proper amount to give the desired generator voltage.

When automatic control for maintaining the generator voltage within close limits is desired, the switch It) is first closed. This supplies current to the primary windings i5 and 26 of the transformers which results in the passage of heating currents through the filaments of the electronic tubes l8, II, 21 and 28. Upon the expiration of a sufiicient time interval for the proper heating of the tubes, the pushbutton switch I! is closed momentarily and then allowed to open. Its closure connects the winding 9 across the leads II and I2 which energizes this relay and causes its movable contacts to be shifted from the position shown to engage the upper contacts. The raising oi the contact 9a causes it to engage contact M which is connected through the switch I4 and switch I! now closed to the lead I! and thereby energizes the relay winding 6 by a circuit from the lead I! through switches i3 and I4, contact 9a and thence through the winding 6 to the lead ll. Thewinding 6 then causes its movable contacts to be shifted from the position shown to engage their upper contacts. The contact 8a by engaging the contact 80 closes a circuit from the lead 12 through the contact to and thence through the winding 9 to the lead I I. thus serving to maintain the coil 9 energized after the switch I3 has opened.

The energizing of the coil 9 also causes the movable contacts to and So to engage the fixed contacts 29 and 30 which thereby causes the field winding I of the exciter to be supplied with current from the automatic control apparatus. This control is momentarily in parallel with the previoualy adjusted auxiliary control circuit as regards supplying current to the exciter field winding. Although the energization oi. the relay coil 8 causes the movable contact 9a to engage its upper contact and thereby connect the relay 6 across the leads II and II, the action of the relay coil 5 is subsequent to that of relay 9 and thus will not break the auxiliary control circuit of the exciter field winding by raising the contact 8a, until a momentary period after the relay 9 has moved its contacts to the operating control position. Thus the circuit of the exciter field is not opened when making the transfer from manual to automatic operation. Upon the movement of the contact 811 by the relay 6, the exciter field winding is then subjected to automatic control only.

When it is desired to temporarily interrupt the automatic regulation for the replacement of a tube, or for any other reason, the pushbutton switch I4 is opened momentarily. This interrupts the circuit 01 the relay winding 6 without then affecting the circuit of the winding 9. However, the release of the contact to of the relay 6 closes the circuit of the exciter winding 5 through the manual rheostat I for the resumption of manual control, while the release of the contact 6a opens the circuit 01' the winding 9 permitting its movable contacts to be retracted. This action introduces another break in the circuit or the winding 6 between the contacts 9:: and 9d so that the reclosing of switch i4 cannot energize winding 6 and also disconnects the automatic controlling apparatus from the field winding of the exciter by the separation of the contacts 9b and So from the contacts 29 and I0.

By this sequence of actions, the field circuit oi the exciter is not opened in the transfer from automatic to manual control because the deenergizing of the relay 6 taking place prior to the deenergizing oi the relay 8, the closing of the field circuit through the manual rheostat 1 takes place before the opening of the contacts which interrupt the circuits oi the automatic regulator to the field winding 5. It has been found in practice that there is no objectionable dip in the voltage of the main generator when this change is made and it has been found by tests that the circuit manual control. It will be understood that the relays are the usual forms of commercial relays with yieldable contacts and are indicated in the drawings in the manner shown merely for clearness and simplicity in following the circuit connections.

In this passage from automatic regulation to manual control, the switch it) remains closed and the electronic tubes of the regulator are maintained heated and in condition for again assuming control at any time it is desired to pass from manual control to automatic regulation. Thus there is no delay in requiring the reheating of the tubes before the apparatus is ready for the change to automatic regulation. Thus when it is desired to pass from manual control to automatic control, it is merely necessary to close temporarily the pushbutton switch l3. The automatic regulation will then assume control in the manner already described by the action of the automatic switching means without opening the field circuit of the exciter.

-In the disclosures of Fig. 1, the operator is depended upon to permit a proper time interval to elapse after the initial closing of switch l before temporarily closing the switch 13 in order to permit proper heating of the tubes before the automatic regulation is placed in contr l. In Fig. 2 automatic means is provided for insuring a proper time interval for heating the regulating apparatus after closing of the switch (0 and prevents the operator from changing to automatic regulation before the tubes have been properly heated. However, after the initial heating of the tubes, the operator is enabled to make'the change from automatic regulation to manual control and the reverse, in the manner already described, the tubes being maintained heated in the meantime and avoiding the delay of reheating each time a change is made. In Fig. 2 the same reference characters designate the corresponding parts which have been described with reference to Fig. 1.

In Fig. 2 a time delay relay is introduced in the circuit of the relay coil 9 and the time element is shown. in this instance as being a bi-metallic strip 35 which is connected to the lead l2 and its contact is adapted to engage the contact 36 which is connected to the winding 9 between one of its terminals and the switch l3. The strip 35 is adapted to be heated by a heating winding 31 connected at one terminal to the lead I! and at its other terminal through a resistance 31a to a fixed contact 38 of another relay and thence through the movable contact 38a of the relay to the lead II. The coil 39 of this relay is connected at one terminal to the lead l2 and at the other terminal to a movable contact 611 of the relay 6. When this relay is energized the contact 611 engages a contact ie which is connected to the lead I I The lower terminal of the relay coil 39 is also connected to a fixed contact 38b which is engaged by the movable contact 38a when this relay is energized, the latter being connected to line H. Another movable contact 38c of this relay is connected to a terminal of the pushbutton switch l3; and when this relay is energized, the contact 380 engages the contact 38d which is connected to the lead I2.

When the manual switch It) is open, all the parts assume the position shown in Fig. 2 and at this time the voltage of the generator is subjected to manual control or adjustment by the rheostat I. The thermostatic switch is in its open position at this time. Upon the closing of the switch l0, current is supplied to the transformers of the regulating apparatus and the heating of the tubes is initiated. During the heating period the closing of the pushbutton switch I3 would have no affect because its circuit is open between the contacts 38c and 38d. The closing of switch III also initiates the heating of the bi-metallic switch 35 by a circuit from the lead l2 through the heating coil 31 and resistor 31a to contact 38 and then by the contact 38a to the lead H. After a sufficient period for heating the tubes of the regulator, the thermostatic strip 35 will cause. its contact to engage the contact 36 and thereby close a circult from the lead I! through the thermostatic switch and through the relay coil 9 to the lead II. This energizes relay 9 and its contacts are moved to efiect automatic regulation and also the contact 9a is caused to engage the contact 9d which, as already explained, serves to excite the relay winding 6. Ihis then opens the circuit through the manual rheostat I and maintains the energization of the winding 9 through the action of the movable contact Go, as already explained; The energizing of the winding 6 also causes its movable contact 611 to engage the contact 6e which closes a circuit from the lead ll through the contact 6d and through relay winding 39 to the lead i2. This relay is then energized and causes the contact 38a to engage the contact 38b which closes its holding circuit through the coil 39 across the leads II and 12 which results in this relay being maintained energized even though the relay winding 6 maybe deenergi'zed. The energizing of the relay winding 39 opens the circuit of the heating coil 31 at the contact 38 which interrupts the heating current through the heating coil and thus keeps this circuit open as long as the switch I0 remains closed. This relay when energized also causes the contact 380 to engage the contact 38d which closes the connection from the lead l2 through these contacts to a contact of the pushbutton switch l3. After the circuit of the heater 3! is opened, the strip 35 cools and causes its contact to separate from contact 36.

If at any time it is desired to pass from automatic control to manual control, such as for the purpose of replacing a tube in the regulating apparatus, it is merely necessary to open the pushbutton switch I4 which deenergizes the relay winding 6 which in turn deenergizes the relay 7 winding 9 and thereby transfers to manual control without causing any objectionable dip in the voltage of the generator, as already explained. The deenergizing of the relay windings 6 and 9 does not, however, cause the deenergizing of the relay winding 39 because that is maintained energized by the engagement of the contact 38a with the contact 38b; and it results that in passing to manual control in the manner just de scribed, the heating coil 31 of the thermostatic switch is not subjected to any heating current because its circuit is maintained open by the relay winding 39. Therefore the thermostatic switch which opened after the discontinuance of its heating current by the energization of the winding 39, will not reclose under the assumed conditions.

When it is desired to resume automatic regulation, it is merely necessary to close the pushbutton switch l3 temporarily which will complete the circuit of the relay winding 9 from lead I! through contacts 38d, 38c, switch i3 and thence through the winding 9 to the lead H. The change of connections and sequence of steps then takes place in the manner already described, resulting in the passage from manual control to automatic regulation. When it is desired to remove the automatic regulation for a prolonged period, the switch M will first be opened for securing the sequenceof changes in the manner already described and the switch I0 is then opened. The opening of the latter switch will deenergize the relay winding 39 and cause the parts to assume the position shown in Fig. 2. When it is desired to resume the automatic regulation, it is merely necessary to close the switch I0 which causes the passage of current to the heating elements of the regulating apparatus and to the thermostatic heating coil 31. After a proper heating period, the thermostatic switch will close which causes the resumption of the automatic regulation by the connections and se modifications may be made to suit particular requirements without departing from the scope of the invention.

I claim:

l. The combination oi a dynamo-electric machine having a field winding, automatic means for controlling the current in said field winding and connected in series therewith, said field winding having an auxiliary open circuit, a manual switch, and automatic means controlled by said switch for first closing said auxiliary circuit and then opening the circuit to said automatic means.

2. The combination oi a dynamo-electric machine having a field winding, automatic means tor controlling the current in said field winding and connected in series therewith, said field winding having an auxiliary open circuit, a manual switch, relays controlled by said switch, one of said relays closing said auxiliary circuit and deenergizing another oi said relays, the latter relay then opening the circuit to said automatic means.

3. The combination of a dynamo-electric machine having a field winding, automatic means for controlling the current in said field winding, said field winding having an auxiliary circuit, a relay when deenergized for closing the circuit oi said field winding through said auxiliary circuit, a second relay when deenergized for opening the circuit between said field winding and said automatic means, a manual switch ior energizing said second relay for closing the circuit between said field winding and said automatic means, connections for energizing the first named relay by the energization 01 said second relay and thereby causing said first named relay to open the circuit between said field winding and said auxiliary circuit, and connections for causing said second relay to be maintained energized by the energization or said first named relay after said manual switch has been opened.

4. The combination of a dynamo-electric machine having a field winding, automatic means for controlling the current in said field winding. said field winding having an auxiliary circuit, a relay when deenergized for closing the circuit of said field winding through said auxiliary circuit, a second relay when deenergired for opening the circuit between said field winding and said automatic means, a manual switch for energizing said second relay for closing the circuit between said field winding and said automatic means, connections for energizing the first named relay by the energization of said second relay and thereby causing said first named relay to open the circuit between said field winding and said auxiliary circuit, connections ior causing said second relay to be maintained energized by the energizetion of said first named relay after said manual switch has been opened, and a second manual switch for deenergizing said first named relay which relay then deenergizes said second relay.

5. The combination oi a dynamo-electric machine having a field winding, automatic means for controlling the current in said field winding, said automatic means requiring a time interval ior attaining operating condition, said field winding having an auxiliary circuit, a relay when deenergized for closing the circuit 01' said field winding through said auxiliary circuit, a second relay when denergized for opening the circuit between said field winding and said automatic means, a switch ior supplying energy to said automatic means and for preliminary conditioning of said automatic means,'a manual switch for energizing said second relay for closing the circuit between said field winding and said automatic means, said manual switch deriving current from said first named switch, connections for energizing the first named relay by the energization oi said second relay and thereby causing said first named relay to open the circuit between said field winding and said auxiliary circuit, and connections for causing said second relay to be maintained energized by the energization of said first named relay aiter said manual switch has been opened.

6. The combination of a dynamo-electric machine having a field winding, automatic means for controlling the current in said field winding, said automatic means requiring a time interval ior attaining operating condition, said field winding having an auxiliary circuit, a relay when deenergized for closing the circuit 01' said field winding through said auxiliary circuit, a second relay when deenergized for opening the circuit between said field winding and said automatic means, a switch for supplying energy to said automatic means and for preliminary conditioning of said automatic means, a manual switch for energizing said second relay for closing the circuit between said field winding and said automatic means, said manual switch deriving current irom said first named switch, connections for energizing the first named relay by the energization 01' said second relay and thereby causing said first named relay to open the circuit between said field winding and said auxiliary circuit, connections for causing said second relay to be maintained energized by the energization of said first named relay after said manual switch has been opened, and a second manual switch for deenergizing said first named relay which relay then deenergizes said second relay.

. 7. The combination of a dynamo-electric machine having a field winding, automatic regulating means for controlling the current in said field winding, said automatic regulating means requiring a time interval for attaining operating condition, said field winding having an auxiliary circuit, a switch for supplying energy to said automatic regulating means and for preliminary conditioning of said automatic means, a time delay relay supplied with energy from said switch, automatic switching means controlled by said relay for first closing the circuit between said field winding and said automatic regulating means and then opening the circuit between said field winding and said auxiliary circuit, and a manual switch for causing said switching means to first close the circuit between said field winding and said auxiliary circuit and then open the circuit between said field winding and said automatic regulating means.

8. The combination of a dynamo-electric machine having a field winding, automatic regulating means for controlling the current in said field winding, said automatic regulating means requiring a time interval for attaining operating condition, said field winding having an auxiliary circuit, a switch for supplying energy to said automatic regulating means and for preliminary conditioning of said automatic means, a time delay relay supplied with energy from said switch, automatic switching means controlled by said relay for first closing the circuit between means and then opening the circuit between said field winding and said auxiliary circuit, and a manual switch for causing said switching means to first close the circuit between said field winding and said auxiliary circuit and then open the circuit between said field winding and said automatic regulating means, said switching means including means for rendering said time delay relay inefiective until after said first named switch has been opened and reclosed.

9. The combination of a dynamo-electric machine having a field winding, automatic regulating means for controlling the current in said field winding, saidautomatic regulating means requiring a time interval for attaining operating condition, said field winding having an auxiliary circuit, a switch for supplying energy to said automatic regulating means and for preliminary conditioning of said automatic means, a time delay relay supplied with energy from said switch, automatic switching means controlled by said relay for first closing the circuit between said field winding and said automatic regulating means and then opening the circuit between said field winding and 'said auxiliary circuit, a manual switch for causing said field winding and said-auxiliary circuit and then open the circuit between said field winding and said automatic regulating means, and a second manual switch for causing said switching means to first close the circuit between said. field winding and said automatic regulating meansand then open the circuit between said field winding and said auxiliary circuit independently of said time delay relay.

10. The combination of a dynamo-electric machine having a field winding, automatic regulating means for controlling the current in said field winding, said automatic regulating means requiring a time interval for attaining operat-- ing condition, said field winding having an auxiliary circuit, a switch for supplying energy to said automatic regulating means and for preliminary conditioning of said automatic means, a time delay relay supplied with energy from said switch, automatic switching means controlled by said relay for first closing the circuit between said field winding and said automatic regulating means and then opening the circuit between said field winding and said auxiliary circuit, a manual switch for causing said switching means to first close the. circuit between said field winding and said auxiliary circuit and then open the circuit between said field winding and said automatic regulating means, and a second manual switch for causing said switching means to first close the circuit between said field wind-.

ing and said automatic regulating means and then open the circuit between said field winding and said auxiliary circuit independently of said time delay relay, said switching means including means for rendering said second manual switch inefiective until after said time delay relay has actuated said switching means.

11. The combination of a dynamo-electric machine having a field winding, automatic regulating means for controlling the current in said field winding, said automatic regulating means requiring a time interval for attaining operating condition, said field winding having an auxiliary circuit, a switch for supplying energy to said automatic means and for preliminary conditionenergized for closing the circuit of said field winding through said auxiliary circuit, a second relay when deenergized for opening the circuit between said field winding and said automatic means, a time delay relay supplied with energy by said switch and for energizing said second relay after a time interval from the closing of said switch, said second relay when energized closing the circuit between said field winding and said automatic means, connections for energizing the first named relay bythe energization of said second relay and thereby causing said first named relay to open the circuit between said field winding and said auxiliary circuit, con nections for causing said second relay to be maintained energized by energization of said first named relay after said time delay relay has been disconnected from said second relay, and a manual switch for deenergizing said first named relay which relay then deenergizes said second relay.

12. The combination of a dynamo-electric machine having a field winding, automatic regulating means for controlling the current in said field winding, said automatic regulating means requiringa time interval for attaining operating condition, said field winding having an auxiliary circuit, a switch for supplying energy to said automatic means and for preliminary conditioning of said automatic means, a relay when deenergized for closing the circuit of said field I ond relay when deenergized for opening the circuit between said field winding and said automatic means, a time delay relay supplied with energy by said switch and for energizing said second relay after a time interval from the closing of said switch, said second relay when energized closing the circuit between said field winding and said automatic means, connections for energizing the first named relay by the energization of said second relay and thereby causing said first named relay to open the circuit between said field winding and said auxiliary circuit, connections for causing said second relay to be maintained energized by energization of said first named relay after said time delay relay has been disconnected from said second relay, a manual switch for deenergizing said first named relay which relay then deenergizes said second relay, and a second manual'switch for energizing said second relay independently of said time delay relay.

13. The combination of a dynamo-electric machine having a field winding, automatic regulating means for controlling the current in said field winding,- said automatic regulating means requiring a time interval for attaining operating condition, said field winding having an auxiliary circuit, a switch for supplying energy tosaid automatic means and for preliminary conditioning of said automatic means, a relay when deenergized for closing the circuit of said field winding through said auxiliary circuit, a second relay when deenergized for opening the circuit between said field winding and said automatic means, a time delay relay supplied with energy by said switch and for energizing said second relay after a time interval from the closing of said switch, said second relay when energized closing the circuit between said field winding and said automatic means, connections for energizing the first named relay by the energization of said second relay and thereby causing said first named relay to open the circuit between said field winding and said auxiliary circult, connections for causing said second relay to be maintained energized by energization of said first named relay after said time delay relay has been disconnected from said second relay, a manual switch for deenergizing said first named relay which relay then deenergizes said second relay, and a second manual switch for energizing said second relay independently of said time delay relay, said switching means including means for rendering said second manual switch ineffective until after said time delay relay has actuated said switching means.

14. The combination of a dynamo-electric machine having a field winding, automatic regulating means for controlling the current in said field winding, said automatic regulating means requiring a time interval for attaining operating condition, said field winding having an auxiliary circuit, a switch for supplying energy to said automatic means and for preliminary conditioning of said automatic means, a relay when deenergized for closing the circuit of said field winding through said auxiliary circuit, a second relay when deenergized for opening the circuit between said field winding and said automatic means. a time delay relay supplied with energy by said switch and for energizing said second relay after a time interval from the closing 01 saidswitch, said second relay when energized closing the circuit between said field winding and said automatic means, connections for energizing 5 the first named relay by the energization of said second relay and thereby causing said first named relay to open the circuit between said field winding and said auxiliary circuit, connections for causing said second relay to be maintained energized by, energization of said first named relay after said time delay relay has been disconnected from said second relay, a manual switch for deenergizing said first named relay which relay then deenergizes said second relay, said 1,,

RUFUS A. ANDREWS. 

